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From ShaoFeng Shi <shaofeng...@apache.org>
Subject Re: Slow Query Performance With 'WHERE' Clause
Date Mon, 22 Oct 2018 14:31:15 GMT
Hi Shrikant,

What's the order of the dimensions in the rowkey? In this case, you need to
put "d3" at the heading position of the rowkey.

Here is a good reference on how to design a cube, maybe we need add that
into the FAQ or as a part of document:
https://www.slideshare.net/YangLi43/design-cube-in-apache-kylin

Shrikant Bang <b.shrikant28@gmail.com> 于2018年10月22日周一 下午3:51写道:

> Hi Team,
>
> We are working on benchmark test for Kylin v2.5-Hbase-1.x as part of PoC.
>
> Here is my cube (pseudo) :
>
> *Dimension Table* : D1
> *Fact Table* : F1, F2
>
> *Metrics* : SUM(D1.m1), SUM(D2.m2)
> *Dimension Columns* -- Normal (D1.d1, D1.d2, D1.d3, F1.a1, F2.b1 )
>
> JOIN (D1.d1 = F1.a1 AND D2.d2 = F2.b1)
>
> When I run a query matching to the cuboids it runs very fast :
> pseudo example query:
>
> SELECT SUM(D1.m1), SUM(D2.m2), d1, d2, d3
> FROM D1
> JOIN F1
> ON D1.d1 = F1.a1
> JOIN F2
> ON D1.d2 = F2.b1
> GROUP BY d1, d2, d3
>
>
> But when I add where clause to query it become very slow in response
> pseudo example query:
>
> SELECT SUM(D1.m1), SUM(D2.m2), d1, d2, d3
> FROM D1
> JOIN F1
> ON D1.d1 = F1.a1
> JOIN F2
> ON D1.d2 = F2.b1
> *WHERE d3 > 100 AND d3 < 1000*
> GROUP BY d1, d2, d3
>
> *In my case d3 is High Cardinality dimension which is part of row key (
> Normal Dimension ).*
>
> Here are question:
>
> 1. I have installed Kylin Co-Processor
> <http://kylin.apache.org/docs20/howto/howto_update_coprocessor.html> before
> running queries. Do Kylin query results gets filtered Co-Processor end?
>
> 2. How to find query traces to identify the bottleneck in response time?
>
> 3. Even though I have enabled Query Cache, it seems its not getting used
> when query runs ( in case of multiple times also) .
>
> 4. Any best practises to tune the queries with WHERE clause?
>
>
> Thank You,
> Shrikant Bang.
>
>


-- 
Best regards,

Shaofeng Shi 史少锋

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